This invention relates to apparatus for controllably blending a continuous stream of small proportionate amount of a first liquid more dense than natural water with a continuous stream of a pumped natural water carrier liquid in such a manner that when the volume of water carrier liquid being pumped is significantly varied, the ratio by volume of first liquid to volume of carrier liquid can be controlled precisely to that ratio predetermined for the particular flow volume of water carrier liquid. More particularly, the present invention relates to a golf course irrigation system using one or more pumps drawing water from a reservoir or well and pumping it through fixed and buried underground pipe lines to pop-up sprinkler or irrigation outlets. More particularly, the present invention relates to apparatus for controllably blending a relatively minute continuous stream of liquid fertilizer of specific gravity greater than 1.15 more or less into a relatively large volume flowing water stream of specific gravity which equals 1.00 more or less; allowing and providing a "spoon feeding" or "syringing" of very small amounts of liquid fertilizer each time irrigation is required on a golf course.
In golf course irrigation systems, the requirement for turf irrigation water is typically supplied by a multiple pump station consisting of one or more synchronous speed electric motors driving turbine or centrifugal pumps and pumping through an automatic pressure reducing and pressure sustaining control valve such as those manufactured and supplied by Cla-Val Co. of Newport Beach, Calif. This particular type of valve automatically performs two important functions. The first function maintains a constant downstream pressure regardless of fluctuating demand. The second function sustains the upstream pressure to a pre-determined minimum. Typically, the automatic control valve is a single seated, hydraulically-operated, pilot-controlled, diaphragm type globe valve.
The control system consists of a reducing control sensitive to down-stream pressure changes, and pressure sustaining control that is sensed to the main valve inlet. The reducing control responds to slight downstream variations in pressure and immediately controls the main valve to maintain the desired downstream pressure. The pressure sustaining control is normally held open by the upstream pressure, but closes if this pressure drops to the control set point. This in turn closes the main valve to sustain the desired upstream pressure. The pressure sustaining and pressure reducing valve, hereinafter called Cla-Val.TM., is adjustable to provide a constant downstream flowing line pressure regardless of the pumped inlet volume and pressure. A typical installation may provide a flowing line pressure immediately downstream of the Cla-Val(.TM.) of 150 psi with the flowing line pressure immediately upstream of the Cla-Val(.TM.) of 200 psi. The various areas of the golf course to be irrigated typically may consist of separate irrigation zones such as fairways, tees, greens, and green banks which are irrigated separately from the rest of the course in a given irrigation cycle. The fairways consist of much larger area of turf grass as compared to the tees or greens; therefore, it is necessary that a greater water volume be pumped in order to adequately irrigate these larger areas in a given time period. The Cla-Val(.TM.) is used to provide a more or less constant operating pressure to the various sprinkler heads, and this pressure must be maintained at substantially that operating pressure recommended by the sprinkler manufacturer. These Cla-Val(.TM.) have been used in this application for many years and their use and application is well known.
In very recent years, in order to reduce electrical energy usage in the pumping of water, variable speed electric motors driving turbine or centrifugal pumps have been utilized. A pressure sensing device is used in the discharge pipe line and is connected to a feed-back electrical control which is used to increase or decrease pump speed to maintain a pre-set desired pressure in the discharge pipe lines. Theoretically, this method eliminates the Cla-Val(.TM.) and is more cost efficient than the aforementioned system using synchronous speed motors and a Cla-Val(.TM.).
Golf courses are typically irrigated during those hours when the course is not being used for play and irrigation may be required daily; therefore, available irrigation time is limited and large volumes of water must be pumped in a relatively few hours and usually during the nighttime hours. A frequently used term related to irrigation practices is the "evapotranspiration rate." It is a measure of the total amount of water lost by evaporation from the soil plus the water lost from plants through transpiration. The daily water use rate varies substantially from climatic region to region and to a certain degree from location to location within an individual golf course. Environmental factors controlling the evapotranspiration rate include the solar radiation level, surface temperature, atmospheric humidity, and wind velocity. Evapotranspiration rates are highest on sunny days characterized by high temperature, low relative humidities, and a moderate wind velocity.
In order to provide the greater amount of water volume to irrigate a larger area of the golf course, one or more additional pumps are brought on line. In the case of a typical 18-hole golf course, three pumps of approximately 1100 gpm pumping rate may be used for irrigating the fairways; whereas, only one of these pumps might be used for the tees and perhaps two of these pumps may be used for the greens, since the greens typically consist of a much larger area of turf grass than the tees and are much less area than the fairways. Typically, greens should be irrigated with their specific needs as related to the particular species of turf grass used, soil texture, topography, climatic exposure, evapotranspiration rate, intensity of play traffic, and root zone depth. Generally, high intensity of play necessitates increased irrigation frequency.
Fertilizer typically should be applied to turf grasses as used on golf courses with precise uniformity of distribution, as it relates to water utilization; with the amounts of fertilizer required per unit area varying according to the different types of turf grass species used on fairways, greens, and tees. Precise uniformity of water and fertilizer decreases waste of the expensive fertilizer, prevents burning of the turf grasses, and eliminates unsightly and uneven growth in the golf course turf grasses. Waste is minimized by applying the precise relationship of fertilizer and water on all areas under irrigation. Burns are prevented by applying the agronomically correct formulation of spoon fed fertilizer in all areas, depending upon the type of turf grasses used and the amount of irrigation required to sustain appearance and health of the grasses. Uneven growth and unsightly patches of turf grass are eliminated by precise, agronomically correct formulations of fertilizer applied in very small amounts continuously as irrigation is performed.
Turf grass fertilizers are formulated and manufactured in both granular dry form and liquid form and are readily available to the operators of both public and private golf course facilities. The inadequacies of dry fertilizer application are well known, since its use absolutely requires dissolving it in place by the action of water, which has proven to be very difficult, ineffective, and wasteful of irrigation water.
Further, its use requires a precise distribution method to help prevent the aforementioned problems of waste, burning and uneven growth of the turf grasses; and, this has been proven to be extremely difficult due to the types of equipment and practices used. These problems inherent to the use of dry, granular fertilizer are well known in the industry.
In known liquid fertilizer applications, the fertilizer is pre-mixed in mixing vessels and is sprayed onto the turf grasses by means of tractor pulled spray equipment. This method is labor intensive and causes uneven application of fertilizer because it requires precise control by the operator of the spray equipment; furthermore, during the "watering in" process the ratio relationship of water/fertilizer per treated area is usually disproportionate, thereby resulting in the same problems inherent to the dry fertilizer and water application methods.
Known prior art devices include those disclosed in U.S. Pat. Nos. 3,202,164, 3,421,738, and 4,456,176. U.S. Pat. No. 3,202,164 discloses a chemical additive device which is said to maintain a preselected concentration of additive in the flow line by introducing the additive in quantities which are in direct proportion to the rate of flow of liquid through the line.
U.S. Pat. No. 3,421,738 discloses a mixing arrangement and in particular to an arrangement for mixing two liquid phases, and is said to admix a first liquid phase, obtained by dissolving a soluble particulate material with another liquid phase at a precisely determined ratio.
U.S. Pat. No. 4,456,176 discloses an apparatus consisting of a storage tank and a solution tank arranged so that high pressure water is fed into the top of the storage tank, thus forcing a chemical additive into the solution tank in such a manner as to agitate the water and chemical additive in the solution tank; thence, into irrigation lines by means of a pump.
Thus, a need exists for an effective, non-labor intensive, uncomplicated apparatus which blends an agronomically correct amount of liquid fertilizer into the irrigation water and allows the operator to "spoon-feed" or "syringe feed" his turf grasses continuously as the golf course is irrigated. Moreover, a need exists for apparatus wherein the ratio of continuous flowing volume of liquid fertilizer to the continuous flowing volume of irrigation water can be automatically controlled, at different ratios, regardless of the pumped flow rate of irrigation water. Moreover, a need exists for apparatus wherein the aforementioned ratio can be preset to any desired value by the operator to automatically provide the same or different ratios depending upon the pumped flow rate of irrigation water, and also depending upon the particular areas of the golf course being irrigated at any given time in the daily irrigation cycle. Satisfaction of these needs allows the operator to "spoon-feed" or "syringe-feed" the various turf grass areas of his golf course according to the varying fertilizer and irrigation demands of such area. For example, the operator may wish to apply twice as much fertilizer per unit of irrigation time to the golf course greens, because of the different turf grass species used, as he applies to the fairways; regardless of the pumped flow rate of irrigation water.